1. Field of the Invention
The present invention relates to a transparent conductive film or transparent conductive sheet with a cured layer and transparent conductive thin film successively layered on a transparent plastic film base as well as a touchpanel using the same. More particularly, the present invention relates to a transparent conductive film or transparent conductive sheet with excellent resistance to pen sliding when used for a touchpanel for pen input as well as a touchpanel using the same.
2. Description of the Background Art
Transparent conductive films with a transparent thin film having small resistance layered on a transparent plastic film base are widely used in electrical and electronic fields, e.g., in a flat panel display such as a liquid crystal display or an electroluminescence (EL) display and a transparent electrode for a touchpanel.
Recently, due to a proliferation of portable information terminals, notebook computers with touchpanels and the like, the demand for a touchpanel with excellent resistance to pen sliding has been on the increase.
When input is made to a touchpanel by a pen, transparent conductive thin films on the sides of a fixed electrode and a movable electrode (film electrode) are brought into contact. Therefore, a transparent conductive film with excellent resistance to pen sliding is required which has sufficient resistance to a load applied by the pen to prevent cracks, separation and the like.
However, a conventional transparent conductive film suffers from the following problem.
A transparent conductive film (Japanese Patent Laying-Open No. 2-66809) has been proposed having a transparent conductive thin film on a transparent plastic film base with a thickness of 120 xcexcm or smaller applied to another transparent base by a tackifier layer. However, after a 100,000 linear-sliding test with a load of 5.0N using a polyacetal pen, which will later be described in conjunction with a sliding-resistance test, it was found that separation was caused to the transparent conductive thin films and resistance to pen input was unsatisfactory. Due to whitening of the separated portion, a display quality decreases when used for a display with a touchpanel.
A transparent conductive film with a layer formed by hydrolysis of an organosilicon compound on a transparent plastic film base and further having a crystalline transparent conductive thin film layered thereon has been proposed for example in Japanese Patent Laying-Open No. 60-131711, No. 61-79647, No. 61-183809, No. 2-194943, No. 2-276630, and No. 8-64034.
However, such a transparent conductive film is extremely fragile because of its crystallinity and small thickness. Thus, after a 100,000 linear-sliding test with a load of 5.0N using a polyacetal pen which will later be described in conjunction with a sliding-resistance test, cracks are caused to the transparent conductive thin film. In addition, since a thermal treatment at about 150xc2x0 C. is required after sputtering the transparent conductive thin film, such a film involves high process cost.
Further, a conductive plastic layer stack with a transparent conductive thin film formed on a curable coating layer has been proposed in Japanese Patent Laying-Open No. 2-5308 and No. 2000-62074. However, although the layer stack is sufficient for use as a transparent electrode of a liquid crystal display, it does not have sufficient sliding-resistance when used for a touchpanel. This is because a residual volatile component is gasified from the cured coating layer during fabrication of the transparent conductive thin film, whereby the quality of the transparent conductive thin film decreases.
In view of the above, an object of the present invention is to provide a transparent conductive film or a transparent conductive sheet which exhibits excellent resistance to pen input when used for a touchpanel and, in particular, which prevents breakage of a the transparent conductive thin film even after a 100,000 sliding test with a load of 5.0N using a polyacetal pen which will later be described in conjunction with a sliding-resistance test, as well as a touchpanel using the same. The transparent conductive film, transparent conductive sheet and touchpanel of the present invention which solve the aforementioned problem are set forth in the following.
Namely, the present invention is a transparent conductive film having a cured layer mainly containing a curable resin and a transparent conductive thin film successively layered on a transparent plastic film base, which is characterized in that 3-200 protrusions, each having a diameter of 0.05-3.0 xcexcm and a height of 0.005-2.00 xcexcm, are formed per 100 xcexcm2 over a surface of the transparent conductive thin film.
According to another aspect of the present invention, the transparent conductive film is characterized in that the curable resin is an ultraviolet-curable resin, a resin which is insoluble with the ultraviolet-curable resin is a polyester resin having an average molecular weight of 5,000-50,000, and the polyester resin is contained in an amount of 0.10-20 parts by weight with respect to 100 parts of the ultraviolet-curable resin.
According to another aspect of the present invention, the transparent conductive film is characterized in that the transparent conductive thin film is formed of an indium-tin oxide compound or a tin-antimony oxide compound.
According to another aspect of the present invention, the transparent conductive film is characterized in that a hardcoat layer is formed on the transparent conductive film on the side opposite the transparent conductive thin film.
According to another aspect of the present invention, the transparent conductive film is characterized in that the hardcoat layer has an anti-glare effect.
According to another aspect of the present invention, the transparent conductive film is characterized in that the hardcoat layer is subjected to a treatment for low reflection.
According to another aspect of the present invention, the transparent conductive sheet is characterized in that a transparent resin sheet is applied to the transparent conductive film by a tackifier on the side opposite the transparent conductive thin film.
According to another aspect of the present invention, in a touchpanel having a pair of panel plates with the transparent conductive thin films arranged through a spacer such that the transparent conductive films are opposite each other, the touchpanel is characterized in that at least one panel plate is formed of the above mentioned transparent conductive film or transparent conductive sheet.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.